Coated metal article and method of making the same



Dec. 19, 1950 H. M. BRAMBERRY 2,534,406

COATED METAL ARTICLE AND METHOD OF MAKING THE SAME Filed Sept. 22, 19445 Sheets-Sheet 1 fnverziaf ar y M5 amb'erg/ Dec. l9,' 1950 H. M.BRAMBERRY 2,534,406

COATED METAL ARTICLE AND METHOD OF MAKING THE SAME Filed Sept. 22, 19445 Sheets-Sheet 2 fnezif." iffy/Z5 merau Dec. 19, 1950 H. M. BRAMBERRY2,534,406

COATED METAL ARTICLE AND METHOD OF MAKING THE SAME 5 Sheets-Sheet 3Filed Sept. 22, 1944 fnz/erzi'of Dec. 19, 1950 H. M. BRAMBERRY 2,534,406

COATED METAL ARTICLE AND METHOD OF MAKING THE SAME Filed Sept. 22, 19445 Sheets-Sheet 4 Dec. 19, 1950 H. M. BRAMBERRY I 2,534,406

COATED METAL ARTICLE AND METHOD OF MAKING THE SAME Filed Sept. 22, 19445 Sheets-Sheet 5 13 J5; J0 'fnveruf or:

fircyMBfamZerrg l ?atente d- COATED METAL ARTICLE AND METHOD OF MAKINGTHE SAME Harry M. Bramberry, New Castle, Ind.; Harry M.

Bramberry, Jr., administrator of said Harry M.

Bramberry, deceased, assignor, by direct and mcsne assignments, tohimself Application September 22, 1944, Serial No. 555,377

This invention relates to metal wear surfaces and methods of fillingsuch surface including particularly internal combustion and othercompression engine cylinders, pistons and piston rings, for improvingthe operating characteristics thereof, including effectin the properrunning-in of the parts, which results in minimum oil consumption, andlow blow-by, for long periods of operation.

One of the major difiicultie in the manufacture of internal combustionand other compression engines, is the provision of proper cylindersurface conditions which will impart to the piston and ring wearsurfaces the desirable surface characteristics to establish thenecessary initial compatibility of these surfaces under load andtemperature conditions.

Itis a prime object of this invention to provide an improved metal wearsurface and method for filling such surfaces with compounds that areparticularly applicable to the filling of relieved internal combustionand other compression engine cylinders, to provide a surface conditionthat promotes compatibility of the parts in the shortest possibleinitial run-in time.

It is a more particular object to provide a novel method of applying thecompound which may be readily accomplished at ordinary roomtemperatures, and which forms a tenacious and firm bond with the metal,as well as providing polishing means, imparting to the piston and ringsurfaces an optimum surface finish, which it has been found, materiallyimproves and I shortens the green or run-in time of cylinders so treatedand also greatly enhances the operating life of such cylinders.

It is a further object of this invention to provide a novel method ofbonding a filler compound to the metal surface which results in control.of the thicknes dimension makin it practicable to "provide anappreciable radial thickness of filler effective to let the cooperatingsurfaces of pistons, piston rings and cylinder come into engagementgradually in a manner producing optimum compatibility.

It is a further object to provide a novel method of applying a fillercompound to the metal surfaces which results in a bondbetween the fillerand the metal that increases in hardness as the underlying metal surfaceis approached whereby to compensate for any machined or otherirregularities in the metal parts, including in particular anyirregularities in the peripheral wall of a cylinder.

It is another object to provide a cylinder in- 16 Claims. (Cl. 3092)ternal surface character and pattern in relief that is particularlyadapted to have the intervening recessed channels of a depth which mayresult in an oil consumption which may be slightly higher than normal,which arrangement is particularly effective for the application andreception of a filler compound bonded thereto and functioning to furthercontrol the wear-in between the cylinders and rings as well asfunctioning to control the oil consumption.

A still further object is to provide a novel wear surface for relievedcylinder surfaces, as well as a novel method of applying said compoundto said surface which results in the formation of a graphitic film,firmly bonded to the surface base metal and which has the highlydesirable properties of abrasion resistance to effect a polishing actionto materially decrease the green or run-in time and prevent scufiing,such film also possessin a wetting effect to secure optimum boundarylubrication and lubricant retaining properties, thus enabling theestablishment of a. lacquer-like film over the entire compression ringsurface area after the run-in period is completed.

Other more particular objects, advantages and uses of my invention willbecome apparent from a reading of the following specification taken inconnection with the accompanying drawings which form a part thereof andwherein:

Fig. 1 is an actual photograph of approximately one-half of the interiorsurface of a standard production cylinder, not employing my invention,said surface showing the major thrust side thereof and indicating thecondition of the surface after the green andfinal runs;

Fig. 2 is an actual photograph of a similar portion of the interiorsurface of the same standard production cylinder of the minor thrustside thereof after the green and final runs;

Fig, 3 is'an actual photograph of approximately one-half of the internalsurface on the major thrust side of a cylinder identical to the abovecylinder but formed with my scratchedcross-hatched pattern in relief,with a superimposed plateau surface, and the interior surface beingfilled with the compound in the manner of the preferred embodiment of myinvention;

Fig. 4 shows an actual photograph of a portion of the same cylinder asFig. 3 but on the minor thrust side thereof; I

Fig. 5 shows an actual photograph of a greatly enlarged (substantiallyto l) representative portion of a cylinder interior that has been filledin accordance with the preferred embodiment of my invention and actuallyoperated under severe conditions in a high out-put internal combustionengine; and

Figs. 6 to 9, inclusive, are enlarged sectional views showing thecharacter of the surface of the cylinder of Fig. during difierent stagesof the fillin thereof, in accordance with my invention, and

Fig. is an enlarged sectional view of the cylinder wall of the surfacerelieved type, after the filling process has been completed and thecylinder has been operating in the engine during the green or run-inperiod.

Referring now to the drawings, it is believed that a clear understandingof the nature of the present invention may be best had by a comparisonof actual photographs of cylinder surfaces treated in accordance withthe principles of the present invention, with photographs of cylindersfinished in accordance with conventional present-day methods. Figs. 1and 2, are actual photographs of the major and minor thrust sides of astandard production steel cylinder following the green and final runs.Figs. 3 and 4, on the other hand, are actual photographs of the majorand minor thrust sides of similar cylinders, following the green andfinal runs, said cylinders having been processed in accordance with thepresent invention. An inspection and comparison of these photographswill clearly show the remarkably improved results secured by myinvention.

The cylinder of Fig. 1 was finished in accord-' ance with conventionalpractice which seeks to produce a mirror-like surface finish. Theroughness of such a surface in accordance with present-day practices isof the order of 10 R. M. S. Figs. 1 and 2 clearly show that the cylinderis now fatally defective, and in operation results in excessive oilconsumption. This is due to the surface disturbance or cold-workedcondition shown on these figures, such condition being evidenced by thevertically extending white streaks, as well as by the horizontallyextending disturbed bands at various levels. These streaks and bandsrepresent surface disturbance areas generally referred to as scuffing orscoring, which are imparted b the action of the piston and rings, andwould result in excessive blow-by and high oil consumption.

Turning now to Figs. 3 and 4, the comparison thereof with Figs. 1 and 2is outstanding. The

cylinder surface of Figs. 3 and 4 shows ideal compatibility betweenpiston and piston rings on the one hand, and the cylinder on the other.The scratched, cross-hatched relief pattern with intervening piston andring supporting plateau surfaces shows no evidence of surfacedisturbance. There is no significant evidence of piston ring or pistonskirt cross-head action or marking, such as is present in Figs. 1 and 2.

It is also pointed out that the pistons as well as the rings removedfrom the cylinder of Figs. 3 and 4 showed .even more remarkable results,further substantiating the importance of my invention. This wasevidenced by the fact that while identical pistons and rings were usedin the comparative test, the rings from the cylinder of Figs. 1 and 2were worn and smooth, while those from the cylinder of Figs. 3 and 4still contained the original tool marks thereon.

Turning now to Fig. 5 it is believed that the important aspects of myinvention can be further understood by reference to the actual enlargedphotograph of a portion of the ring engaging surface of an internalcombustion engine cylinder treated in accordance with a preferredembodiment of my invention. This photograph brings out clearly theresults of actually filling a relieved cylinder surface with my improvedfiller compound in the novel manner herein disclosed. This particularcylinder is of the scratched, cross-hatched superimposed plateau typesimilar to that of Figs. 3 and 4. The white diamond-like shaped areasindicate the plateau surfaces against which the rings actually operatewhile the intervening darker areas are composed of my filler compoundbonded to the relieved channels or recesses. While the plateau areasshow up in white in th photograph, it is important to note that theentire ring travel area of the cylinder when removed from the enginefollowing operation under the most severe conditions, was actuallyuniformly coated with a very thin brownish lacquer-like film. Thisuniform lacquer coating results only when optimum antifrictionconditions, optimum oil control conditions and optimum heat removalconditions pre- Vail. All of these optimum conditions are evidenced inthe structure disclosed in this photograph of Fig. 5 as well as thephotographs of Figs. 3 and 4. These photographs show unusual resultsnever heretofore even approached, so far as I am aware.

Turning to Fig. 10, I have indicated schematically a cross-sectionalview taken through the wall of the cylinder shown in Fig. 5 for thepurpose of more readily identifying the component parts of the structureinvolved and describing the manner in which the filling is accomplished.The cylinder here employed for the purpose of describing a preferredembodiment of my invention comprises a section of a cylinder it] havingfirst formed therein a character or pattern preferably by means ofscratched, crosshatched honing to provide recessedscratches H to thedepth of at least .0002" and deeper. This cylinder had a relieved areaof the order of 35 per cent and a corresponding unrelieved area made upof a multiplicity of substantially uniformly disposed pyramidalprotuberances having plateau surface areas l2 which form individualareas. This ratio may vary however from 15 to 60 per cent in relief. Ihave found however, that for a steel cylinder used in a high compressionmilitary aircraft engine, the 35 per cent of relief is most effective.This particular construction of cylinder wall surface, apart from itsnovel combination with the present improved filler compound and methodof applying the same with the accompanying important product and unusualresults obtained, forms the subject matter of my application Serial No.555,379, filed September 22, 1944, for Cylinder surface Character, nowPatent 2,434,880 of January 20, 1948.

Relieved grooves or recesses ll of a cylinder. thoroughly cleaned of anyoil film are first filled to the level of the plateau areas l2 with acompound that will be referred to as a trowelling compound indicatedgenerally at l3, which is of a relatively putty-like consistency.Following this the surface is sprayed with a compound in liquidsuspension which will be referred to as the spraying compound indicatedgenerally at I 4. The cylinder is next preferably allowed to dry forseveral hours and then baked at an elevated temperature, preferablybetween 400 and 600 F., the baking conditions being determined by thedesired degree of hardness of the bond between My improved trowellingcompound consists of ailne or colloidal graphite base, homogeneouslymixed with a plastioizer, in the ratio of one to two parts by weight,respectively. I have found that tricresyl phosphate when employed as theplasticizer yields excellent results, although good results may beobtained by utilizing any of the well-known materials commonly used inplasticizing paints, such as diamyl phthalate or castor oil. While Iprefer to employ the materials in the above ratio, this may be variedifdesired, it being pointed out, however, that if too large a percentageof plasticizer is used, the compound remaining in the channels will besubject to an undesirable degree of shrinkage, during the subsequentoperations. The graphite used should be ground to colloidal size, theresultant particles being of the order of to microns. found that thissmall size is most effective in filling the minute channels ofthe'relieved cylinders.

My improved spraying compound comprises preferably a water in oilemulsion and consists of a fine or colloidal graphite base, a binder,phosphoric acid, a carrier thinner or solvent, and a suitableemulsifier.

There is given below by way of example, one formula for making onegallon of a spraying compound which is a water in oil emulsion andwhichI employed in treating the cylinders shown in Figs.3,4and 5. I

The solvents employed in'the above formula comprised the-following, inthe ratios noted,

Material Gallon. Pounds Xylol Q. .392 2. 760 High Flah Solvent Naphtha.080 .510 "atcr 244 2.033 .716 5.303

In the above formula, the binder is preferably a resin and may be of theclass of petroleum or vegetable residue pitches, it being understood,however, that other suitable resins-may be employed if desired. Thebinder 'used is preferably water insoluble, should be such as to have agood cohesive or cementing action with the graphite, and should be onewhich'does not completely volatilize at the high temperatures of theorder of 400' to 600 F. which may be employed in the process to hastenthe action of the spraying compound. The physical characteristics of,the binder are preferably as follows:

1. Softening point from 155 to 170 F.

2. Penetration from 25 to 35. a

3. Stormer viscosity at 360" F. of from M R. P. M, v

I have so to 60 8 With respect to the acid employed, this is preferablyortho-phosphoric." Other phosphoric acids such as. metaphosphoric, acidand phosphoric anhydri'dehave been used, but are ordinarily lesssatisfactory. In the'formula, the acid has been noted as being of astrength of 75% phosphoric acid. In'the eventthe strength isof" agreater order, it will be understood that the water content iscorrespondingly changed, but that the same ratios are maintained.

The graphite utilized may be natural or synthetic, of ,high quality andpreferably of extremely small particle size. It is preferred to usecolloidal graphite or at least particles approachin the fineness ofcolloidal size.

he solvents, employed, are given by way of example only, since they maybe any suitable solvent for the resin used.

The emulsifying agent employed must be suitable to emulsify water in oilor oil in water. The agent may be of either the cationic 0r non-ionicclasses. In the specific formula given, the emulsifier used was asubstituted polyglycoletheralcohol, an emulsifier of the non-ionic type.However, if desired, the emulsifier may be of the cationic type, such asan amine-amide, for example.

In preparing the spraying compound according to the above formula, theentire amount of resin binder was dissolved in an equal weight of xylol,this resulting in a 50% solids solution. To

this solution was added a graphite dispersion which comprised the entireamount of graphite with an equal weight of xylol. This dispersion wasthus also a 50% solids product and the combination of the resin solutionand graphite dispersion is what is termed the oil phase of the emulsion.

Thereafter, the water phase of the emulsion is obtained by adding theemulsifier and water to the phosphoric acid. Then the oil and waterphases are mixed with violent agitation and the resultant emulsionthinned to spraying viscosity with the high flash solvent and theremainder of the xylol. If desired the resultant compound may befiltered or otherwise treated to remove any undesirable agglomerates andto secure a product with the necessary degree of fineness.

While the foregoing, outlines one method of making my improved sprayingcompound, with certain specific amounts and percentages of materials, Ihave found that certain of the proportions may be varied within limits,and will yield excellent results. I

For example, I have found that I may vary the ratio by weight ofgraphite to binder to from 2 to 1, to 3 to 1. Best results ma beobtained when using an amount of graphite from twice to three times theweight of the binder. This variation has been determined from a widevariety of experiments, and therefrom, I have found that for a ratiohigher than 3 to 1, there is a tendency for the resultant film producedby the spraying compound to become thixotropic or jelly-like in naturewith accompanying undesirable flow properties. Moreover, the resultantfilm does not have the desirable degree of abrasion resistance orpolishing quality.

I have also found that with ratios of less than 2 to 1, the resultantfilmis too soft and less resistant to abrasion than that desired. Hence,my preferred range of ratios, which I have determined results in atenacious film which has the desired degree of abrasion resistance, isthat set forth above.

The chemical or phosphoric acid content of the compound is also a veryimportant variable and may be expressed in a ratio such as Grams of 100%phosphoric acid Grams of total solids limit, the resultant films arelacking in strength and resistance to abrasion and exhibit a lack oftenacious adherence to the cylinder surface. The degree of polishingeflect of such films is decidedly less than that desired in practice.When the ratio exceeds the high limit, the resultant films will not dryproperly, and it was found that they would blister regardless of whetherthe sprayed cylinder was permitted to air dry or was baked. Within thelimits prescribed, the resultant films were highly satisfactory and weresufficiently resistant to abrasion, as to give the required high degreeof polishing effect.

The spray-on compound is applied at ordinary room temperature to athickness of the order of from .003" to .001" above the plateau areas.It is preferred that the cylinder so filled be allowed to dry for aboutfive hours in the case of cylinders of steel or iron. In the case ofchromium surfaced cylinders, the drying time is preferably about tenhours. Such drying is followed by a baking operation at an elevatedtemperature, preferably from 40 to 600 F., for a time period of fromthirty to sixty minutes to produce the desired abrasion resistance ofthe filler, as well as to produce the requisite hard phosphate bondbetween the filler and the underlying metal. In the case of steel andiron cylinders, such bond would be iron phosphate, while in the case ofchromium surfaced cylinders, the bond would be chromium phosphate. Byincreasing the acidity content within the limits heretofore noted, theabrasion resistance can also be increased. It is noted that upon theapproach of the maximum permissible acidity content bubbling will beexperienced prior to the baking or during the baking operation.

With the proper choice of proportions to lit the circumstances of theparticular installation, it is found that a hard phosphate bond resultshaving a final thickness dimension of the order of A with the metal ofthe cylinder surface to form the phosphate in. situ and phosphatedispersed throughout the graphite, thus effecting a, firm cementingaction of the graphite not only within the relieved areas but also onthe plateau surface areas.

It is of further importance to note that by filling the cylinder in thismanner including the formation of the hard phosphate bond,irregularities otherwise present as a result of error in machining orerror due to distortion in operation are compensated for by thishardbond between the filler and the underlying metal. This is veryimportant, since it is substantially impossible to machine or otherwiseform a cylinder ring travel surface perfectly symmetrical.

The trowelling-in of the filling compound l3 may be most effectivelyaccomplished by rotating the cylinder while the trowel is held in properrelation thereto. Fig. 6 shows one of the scratches or grooves l lfilled with the trowelling compound. After this trowelling operation iscompleted and the excess compound removed as shown in Fig. 6, thespraying compound containing the proper proportion of phosphoric acid ispreferably sprayed on in one or more coats, this also being accomplishedwhile rotating the cylinder. While rotation of the cylinder or cylindersis preferable, in applying the trowelling and spray compounds, theinvention is not limited thereto, since the cylinder may be stationaryif desired. By using a phosphoric acid content within the limitsheretofore described, I find that this provides the necessary acidityfor the total volume of the trowelling compound and the spray compound,and avoids difficulties such as bubbling of the trowelling compound andan unsatisfactory resultant film. Fig. 7 shows one of the groovesfollowing the application of the spray compound. The trowelled-incompound immediately absorbs the liquid constituents from the spraycompound so that the two when combined will chemically react as one forboth air drying and baking. Prior to baking, the surface appears likethat in Fig. 8. It will be noted that baking is employed primarily tospeed up the process, since given sufficient time for air drying theinstallation of the filler could be accomplished without baking, onsteel and iron cylinders. The fact that the present filling compoundscan be properly installed and bonded to the wear surface of steel andiron at ordinary room temperatures is considered of particularimportance, especially for automotive enbloc cast iron cylinders. Amongthe other advantages growing out of this unusual property of the presentcompounds is the fact that the same may be installed in the field wherebaking facilities are not available. In comparison, it is noted thatfrom seventy to eighty hours of air drying is required to obtainapproximately per cent of the abrasion resistance and hardeningaccomplished by five to fifteen hours preliminary air drying followed bybaking. Following baking the surface is as shown in Fig. 9, the bottomof the depression over the groove being of the order of .0003." to .001"above the base metal of the cylinder.

Further attention is directed to the apparent lubricating phenomenapresent in a cylinder filled in accordance with the process as abovedescribed.

' Under abnormal engine operating conditions such as that to which thecylinder of Fig. 5 was subjected, it has been found quite common in theusual types of cylinders, for the accompanying detonation to overloadthe cylinder walls with resulting scoring and scuffing, as well ascausing abnormal expansion of the piston. It is noted that no damage isevidenced in the cylinder wall of Fig. 5 and that the same is insubstantially perfect condition. It would appear that these unusualresults are due in part to the porosity and oil absorbing or retainingnature of the herein disclosed filler compounds, acting in the mannerakin to a sponge action to maintain lubricant under abnormal conditions.

As concerns the application of the present inention to relieved cylindersurfaces fundamental importance is attached to the fact that theappreciable thickness dimension of the filler above the metal surface ofthe order of .0003" to .001", together with the hard bond of ironphosphate in the case of iron and steel and chromium phosphate in thecase of chromium surfaced cylinders, results in a gradual wear-in of theparts which is exemplified in the case of the I cylinder assembly by theslow letting downofthe rings and piston onto the cylinder wall with theresulting unusual compatibility. In the-foregoing, I have'described thecombined use of the' troweling and spraying compounds in connectionwiththe filling of cylinders which have been relieved in accordance with myapplication Serial Number 555,379, filed September 22, 1944, forCylinder Surface Character, now Patent 2,434,880 of January 20, 1948. Inthat application, and as pointed out herein, the scratched cross-hatchedrelief pattern provides recesses which are of a depth of at'least.0002", and in the event that the maximum depth of the grooves does notmaterially exceed .0008" the use of the trowelling compound may bedispensed with, in which event one or more coats of the spray compoundhas been found sufiicient to secure the film of desired thickness.

'It is also desired to point out that cylinder surfaces, relieved inmanners other than by the scratched, cross-hatched method may be filledin accordance with my invention. For example, I have filled cylinders inaccordance with the method disclosed herein which were provided withchromium surfaces, relieved electrolytically, with excellent results.The invention is therefore not limited in its application to the fillingof cylinder surfaces which are relieved in an particular manner. Theinvention is furthermore not limited to the treatment of any particulartype of metal cylinder and may be employed for treating cylinders ofiron, steel, steel alloys, aluminum, bronze, chromium or hardenedsurfaces, for example. In the case of the treatment of chromium orhardened'or alloy steel surfaces, the baking step is a necessaryrequisite in order to attain a hard, abrasion resistant film. However, Ihave found that unless the depth of relief, on cylinder surfaces iscarried to at least .0002", the exceedingly highly satisfactory resultsflowing from the present invention and fully set forth herein, will notbe obtained.

,In the event that my improved spray compound is used to coat or fillthe exterior wear surfaces of pistons and piston rings, it will be,understood that such surfaces may be relieved, as set forth herein, ormay be provided with conventional finishes. I have found thatconventional finished surfaces of pistons and piston rings when treatedwith my spray compound, are

such, that when these elements are used in en-' gines, the cooperatingparts within the engine power zone exhibit a new and improvedcompatibility.

While I have described my invention in connection with certain specificapplications thereof,

it will be understood that this is by way of example rather thanlimitation and that the same is to be accorded the scope as defined bythe appended claims.

1. An engine cylinder having a plurality of channels or grooves formedin the ring-engaging surface thereof, and having a continuous filmbonded to said surface and within the channels, said film comprising aphosphate of the metal of the surface and fine graphite.

2. An engine cylinder having relieved areas throughout the ring-engagingsurface thereof, and having a continuous film on said surface andextending into said areas, said film comprising fine graphite firmlybonded to the surface and areas by a phosphate of the metal of thesurface.

3. An engine cylinder having relieved areas said surface having acontinuous film thereon.

and extending into said relieved areas and including graphite and'abinder uniformly bonded to the surface and areas by a phosphate of themetal of the surface.

4. An engine cylinder having a chromium ringengaging surface providedwith a plurality of relieved areas, said surface having a continuousfilm thereon extending into said areas, and comprising fine or colloidalgraphite bonded to the surface and areas by chromium phosphate.

5. An engine cylinder having a ferrous metal ring-engaging surfaceprovided with a plurality of relieved areas, said surface and areashaving a thin, continuous film thereoncomprising fine graphite firmlybonded to the surface and areas by iron phosphate.

6. An engine cylinder having an internal ringengaging surface formedinto a pattern in relief, said surface having a thin, continuous filmthereon, said film comprising fine graphite firmly bonded to the surfaceby a phosphate of the metal of said surface area.

7. An engine cylinder having an internal ringengaging surface formedinto a pattern in relief, said pattern including a plurality of groovesdefining a plurality of protuberances having plateau surfaces forming a.ring-engaging area, said area and grooves having a thin, continuous filmthereon, said film including fine graphite firmly bonded to the area bya phosphate of the metal of said surface.

8. An engine cylinder having an internal scratched, cross-hatchedsurface having character or pattern in relief and including amultiplicity of protuberances separated by said scratches andterminating in ring-engaging deposited said scratches, said whichconsists in relieving at least the ringengaging part of the wear surfacesubstantially uniforml throughout its area by removing from 15 to 60 percent of the metal surface to a depth of at least .0002 inch, thenfilling the relieved areas and covering the unrelieved areas with acompound comprising an emulsion of a fine or colloidal graphite, a resinbinder, phosphoric acid, a solvent for the resin binder, and anemulsifier, the ratio by weight of graphite to binder in the compoundbeing from 2:1 to 3:1 and the ratio by weight of phosphoric acid tobinder and graphite being from 0.10 to 0.80, and then bonding thecompound to the metal of the relieved and unrelieved areas.

10. The method of increasing the load-carrying capacity of the wearsurface of an engine cylinder and improving the compatibility betweenthe wear surface and the piston and piston rings, which consists inrelieving at least the ringengaging part of the wear surfacesubstantially uniformly throughout its area by removing from 15 to 60per cent of the metal surface to a depth of at least .0002 inch, thenfilling the relieved. areas and covering the unrelieved areas with acompound comprising an emulsion of a fine or colloidal graphite, a resinbinder, phosphoric acid, a solvent for the resin binder, and anemulgraphite bonded in place by- 11. The method of treating the wearsurface" of an engine cylinder to improve the load-carrying capacitythereof and to control the flow of oil past the piston, comprising thesteps of relieving at least the ring-engaging part of the wear surfacesubstantially uniformly throughout its area, by. removing from to .60per cent of the metal surface to a depth of .0002 inch or more, fillingsaid relieved areas to a substantially flush condition with a materialcomprising fine or colloidal graphite and a plasticizer, covering thefilled and unfilled areas with a compound which impregnates the materialfilling the relieved areas and which comprises an emulsion of a fine orcolloidal graphite, a resin binder, phosphoric acid, a solvent for theresin binder, and an emulsifier, the ratio by weight of graphite tobinder in the compound being from 2:1 to 3:1 and the ratio by weight of100% phosphoric acid to binder and graphite being from 0.10 to 0.80, andthen bonding said material and said compound to the relieved andunrelieved areas of the wear surface by causing the phosphoric acid ofsaid compound to react with the metal of said relieved and unrelievedareas.

12. An engine cylinder having a chromium ring-engaging surface providedwith a plurality of relieved areas having a depth of at least .0002

inch, said surface having at least initially a conunrelieved areas ofthe wear surface having at a least initially a, continuous film thereoncomprising fine or colloidal graphite bonded to the metal 12 of therelieved and unrelieved areas by a phosphate of the metal. g

14. An article of manufacture having a chromium wear surface providedwith a plurality of relieved areas, said surface having at leastinitially a continuous fllm thereon extending into said areas andcomprising fine or colloidal graphite bonded to the surface and areas bychromium phosphate.

15. An article of manufacture" having a chromium wear surface providedwith a plurality of relieved areas having a depth of at least .0002inch, said surface having at least initially a continuous film thereonextending into said areas and comprising fine or colloidal graphitebonded to the surface and areas by chromium phosphate.

16. An article of manufacture selected from the group consisting ofpistons and piston rings having a relieved wear surface coated at leastinitially with fine or colloidal graphite bonded to the surface by aphosphate of the metal thereof.

HARRY M. BRAMBERRY.

REFERENCES CITED The following references are of record in the file ofthis patent:

. .UNITED STATES PATENTS Number Name Date 974,854 Boggs Nov. 8, 19101,420,551 Ivins -1- June 20, 1922 1,481,936 Thomson Jan. 29, 19241,562,555 Harley Nov. 24, 1925 1,964,671 Nesbitt June 26, 1934 32,032,694 Gertler Mar. 3, 1936 2,121,606 McCulloch June 21, 19382,166,634 Lesa'ge July 18, 1939 2,239,414 1 Eddison Apr. 22, 19412,296,844 Glasson Sept. 29, 1942 40 2,314,604 Van der Horst Mar. 23,1943 FOREIGN PATENTS Number Country Date 420,461 Great Britain 1934474,252 Great Britain 1937 542,302 Great Britain 1942 118,316 Australia1944

